Echo-box microphone



Sept. 14,1926. 1,599,541

A. NYMAN ECHO BOX MICROPHONE Filed April 2. 1924 4 SheetsSheet 1 Fig.1.

WITNESSES: V A IQVENTRR 25 er Y I ATTORNEY A. NYMAN BCHO BOX MICROPHONESept. 14, 1926. 1,599,541

Filed April 2, 1924 4 Sheets-Sheet 2 Fig.2.

III

WITNESSES: INVENTOR A legancler Nyman. u v W Sept. 4 14 1926. 1,599,541

A. NYMAN ECHO Box mcaorabus Filed April 2. 1924 4 Sheets-Sheet 5WITNESSES: I INVENTOR fl Alexander Nym'an.

' ATTORNEY A. NYMAN ECHO Box uIcao'P'nouE Filed April 2, 1924 4Sheets-Sheet 4 v Fig.4.

wnusssss; INVENTOR Alexander Nymcm. I I B Q 7 ATTORNEY Patented Sept.14,

UNITED. STATES.

PATENT ,oFF1cE.-

ALEXANDER NYMAN, 0] EAST ORANGE, NEW JERSEY, ASSIGNOB '10 WE BTINGHOUS EELECTRIC & IANUFAOTUBUG OOIPANY, A CORPORATION 01' PENNSYLVANIA.

ncno-aox incnornoim.

Application fled April 2 My invention relates to apparatus for thetranslation of sound into vibrato electric currents, and particularly todirectionally selective microphone devices.

One of the objects of my. invention is to cohstruct a device forconvertin sound vibrations into electrical vibrations which shallrespond to sound from certain sources more readily than from othersources.

Another ob "ect of my invention is to rovide sound-a sorbing andsound-shiel in means in connection with a micro hone an an attachedelectrical system whic shall respond only to sound from a predeterminedsource thereby generating a vibratory electric current which produces amuch more truthful copy of the sound waves from the predetermined sourcewhen reproduced in a telephone receiver connected to the same electricalsystem.

In the development of the prior art of telephony, microphones haveusually been" enclosed in a light metal case rovided with a small hornfor collecting an transmitting sound to the diaphragm. Relatively fewmicrophone devices have been constructed suitable for sounds other thanspeech and, in their construction, few attempts have been made to avoidresponse IIIJKI the microphone to extraneous sounds. e designers of suchdevices have placed much more'dependence upon the greater sound volumefroma speakers voice when his face is in close proximity to thecollecting horn, as compared with the volume of the extraneous soundpreventing interference between its extraneous sound andspeech. Themicrophone then is sufliciently insensitive to be unresponsive to thelesser sound volume of the exgroup electrical 'secur traneous noises. v

Because of the lack of devices suitahle for the reception of soundfrom-substantial distances, the-collection of sound from a' of musicalinstruments, a chorus, and similar sound sources, and its conversioninto vibratory currents, suitable for pu s such as that of modula arad1osen g apparatus, have been. foun drflicult. Because of thislaclr,the broadcasting of vocal and instrumental music by a radio--' apparatusfrom a sound fpick-up by an ordinary telephone transmitter has beenfound unsatisfactory. Serious interference has been found to occurbesendin 1924. Serial no. 103,064.

phone, it is necessary to distinguish between sounds of two types.Sounds emanating directly from the source to which response is desiredmay be called the primary sounds,

and echoes and other extraneous noises, in-

cludin applause and the ordinary sounds of an au ience, may be calledsecondary sounds. The purpose of my invention is to obtain a principalresponse by a microphone to pri- 7 mary sounds and a minimum response tosecondary sounds.

My invention provides means whereby this preferential response may beobtained which consists of a mlcrophone mountin containing soundchannels within its bo y. These sound channels are directed toward thesource from which it is desired to receive the sound. The channels areformed from sound-absorbent material and are of substantial length. Bythis means, sounds from a direction included within an angle whichsubtends the sides of the channels is allowed to pass directly to themicrophone and I affect it, while sound from sources not included'withinthis angle is caught and absorbed by the sides 0 the sound-conveyingchannel and thereby restrained from influencing the microphone.

, Other objects and structural details of my invention will be apparentfrom the following description, when read in connection with theaccompanying drawings, wherein:

Figurel is a diagrammatic view of the device of my invention, asassociated witha church choir, a choir screen, choir stalls and anorgan, showing the device in. a typical location.

Fig. 2 is *a view, in. longitudinal section, of my device,

Fig. 3 is a view in section, of my device taken at right angles to Fig.2, and

Fig. :1 is a per'spectivev1e w ofjhe device.

of my invention. V v

Fig. l'shows choir stalls 1, a choir screen 2, an organ 3, a choir arch4 and a pick-up microphone 5. The microphone 5 is supported by the cords6 and 7 which are attached to the walls of'the choir arch 4 at ioohidden from the congregation by the choir screen 2, the microphone 5being likewise hidden by the same means.

Referring to Figs. 2, 3 and 4, a microphone 5 comprises asound-responsive element 11 that is supported by elastic cords within acontaining envelope. This container com: prises a cylinder 13' ofMicarta, fiber, metal, or other suitable material, and perforated atsuitable points according to the position of the device with respect tothe sound sources, to the output of which it is desired that themicrophone respond. This cylinder encloses a series of concentric feltcylinders 14 to 19, inclusive. The ends of cylinder 13 are closed bywalls 21 and 22 of similar material which is faced with felt disks 23and 24. Supporting means 25 and 26, 27 and 28 serve to hold the feltcylinders in concentric positlon surrounding microphone 11. Other feltdiscs 29, 31, 32, 33, 35 and 36 are provided within the interior ofcylinder 19 supported by means 25 and 26, 27 and 28. Openings 37, 38 and39, and 40 are also provided.

Circular hoops 43 to 46, inclusive, are also provided for maintainingthe proper shape of the interior ofthe concentric felt cylinders. Hooks42 are attached to the eX- terior of the cylinder 13 for supportingmeans. Referring particularly to Fig. 3, the sound-sensitive microphonedevice 11 is supported on elastic cords 12 within the containingcylinder 13.

Spacing means 41 are placed between the successive felt cylinders 14 to19, inclusive, these spacing means being felt strips which are repeatedabout the axis of the cylinder at a 90 spacing.

In the construction of my device, I provide opening 37 to 40, inclusive,so disposed with respect to microphone 1 1 that,

when the assembly is supported adjacent to,

the sources of sound to which it is desired that the microphone respond,the openings are respectively directed toward these sources. Thesesuccessive openings through the various felt cylinders are graduated insize and made to subtend an angle, with its vertex in the center of themicrophone, equal to the angle which subtends the lines drawn from thecenter of the microphone to the boundaries of the space occupied by thesound source. This is indicated in Fig. 1 by lines 53 to 56 inclusive.-

This construction permits sound coming labyrinth of openings between thefelt cylinders and are there absorbed and destroyed, by which means thesecondary sound is prevented from affecting the microphone 11.

In Fig. 1, microphone device 5 is shown supported by cords 6 and 7. Ithas been found that loud organ music causes vibration of the entirestructure of the building and such vibration, transmitted to amicrophone, causes an objectionable rattling effect.- This ditficulty isavoided -by the supporting cords 6 and 7 which carry the weight of themicrophone device and hold it in position butdo not transmit vibrationto it.

In the operation of my device, I construct a sound-shielding means, aspreviously described, adapting the openings through the felt cylindersto the particular location in which the device is to be used. I thensupport the device so that the various openings are directed toward therespective sources which it is desired to receive, as shown in Fig. 1. Imay then energize the microphone with electric current and it willrespond to sound from the desired sources, since such sound is free toenter through the openings in the felt cylinders and impinge upon thetransmitter.'

Sounds from other sources do not, however, enter the openings in such away as to reach the microphone, but enter the labyrinth between the feltcylinders and are absorbed and thereby restrained from reachmg themicrophone 11.

By this means, I am able to construct a shielding means which,surroundin a microphone, contains sound-conveying c annels adapted toconvey sound from predetermined sources to the microphone 11, and amable to prevent sound from other sources from impinging upon microphone11. In this way, I am able to obtain preferential response of themicrophone 11 to primary sounds, as compared with secondary sounds.

VVhile I have shown only one embodiment of my invention in theaccompanying drawings, it is capable of various changes andmodifications without departing from the spirit thereof, includingchanges inan-- gles subtended by the openings through the felt cylindersand changes in the number of openings, as well as other changes, and itis desired, therefore, that only such limitations shall be'imposedthereon as are indicated in the prior art or in the appended claims.

I claim as my invention:

1. A directive reception microphone comprising, in combination, asound-responsive device and a plurality of concentric perforatedsound-damping elements surround ing said instrument.

2. A directive reception microphone comprising, in combination, asound-res onsiv'e device, a plurality of concentric, per orated,sound-damping and sound-absorbing means surrounding said instrument, andspacing devices, said damping devices being space apart by said spacingdevices.

3. A directive reception microphone device comprising a sound-sensitivedevice and a surrounding sound-absorbing device, said absorbing devicebeing provided with soundconveying channels, said channels ,beindisposed to convey sound from certain irections only tosaid'sound-sensitive device.

4. A directive reception microphone device comprisin a sound-sensitivedevice, in combination with a sound-conveying device, said conveyingdevice comprising a plurality of sound-absorbing containers perforatedwith a plurality of cooperating sound channels.

5. In a sound-responsivesystem, in combination, a microphone, and asurrounding plurality of sound-absorbent means having perforationsconstituting .channels leading to said microphone. v

6. .In a sound-responsive system, in combination, a microphone, and a,surrounding plurality of sound-absorbent means havingv perforationsconstituting channels leading to said microphone, said channels beingdirected toward the predetermined sources of sound. I

7. The combination of a microphone and a plurality of sound-absorbentmeans having a plurality of sound-conveying channels therein.

8. The combination of a microphone and a plurality of sound-absorbentmeans having a plurality of sound-conveying channels therethrough, saidabsorbent means com prising a plurality of perforated felt cyliners. I

9. The combination of a microphone and a plurality of'sound-absorbentmeans having a plurality of sound-conveying channels therethrough, saidabsorbent means comprising a plurality of perforated felt cylindersconcentrically surrounding said microphone.

10. The combination of a microphone and a plurality of sound-absorbentmeans having a plurality of sound-conveying channels therethrough, saidabsorbent means comprising a plurality of perforated felt cylindersconcentrically surrounding said microphone, said perforations formingsaid sound channels and being disposedsymmetrically with respect to aradiuscommon to all of said cylinders.

11. The combination of a microphone and a plurality of sound-absorbentmeans having a plurality of sound-conveying cliannels therethrough, saidabsorbent means comprising a plurality of perforated felt cylindersconcentrically surrounding said microphone, said perforations formingsaid'sound channels and being disposed symmetrically with respect to aradius common to all of said cylinders, said common radius beingdirected toward the source 'of primarysound.

12. The combination of a microphone and a plurality of sound-absorbentmeans having a plurality of sound-conveying channels therein, saidabsorbent means comprising a plurality of perforated felt cylindersconcentrically Surroundin said microphone, and felt spacing mem erspositioned between said felt cylinders.

13. The combination of a microphone, a plurality of sound-absorbentmeans, a container and supporting and positioning means, said absorbingmeans and said container having sound-conveying channels therethrough,said absorbent means comprising a plurality of perforated felt cylindersconcentrically surrounding said microphone, said container coin rising afibrousmaterial tube, said tube eing also perforated for said soundchannels.

14. The combination of a microphone, a plurality of sound-absorbentmeans, a container and sup orting and (positioning means, said absor ingmeans an said container having sound-conveying channels therethrough,said absorbent means comprising a plurality of perforated felt cylindersconcentrically surrounding said microlplhone, said container comprisinga solid brous-material tube, said tube being also perforated for saidsound channels, said perforations forming said sound channels and. beingdisposed symmetrically with re- (sipect to a radius common to all ofsaid cyliners.

15. In combination, an auditorium in-.

eludin a part adapted for a program, a microphonea means associated withsaid microphone for hindering the arrival of sounds from certaindirections, whereby the microphone is selectively sensitive to soundsfrom predetermined directions, and means for supporting the microphoneand its associated means in such a position that the said predetermineddirections are toward the art of the auditorium where the program istobe performed.

16. In combination, an edifice including a portion adapted for programs,a microphone, means for rendering the microphone selectively-responsiveto sounds from a redetermined direction and supports exten ing from thewalls of the edifice for maintaining the microphone and said means insuch position that said predetermined direction is toward the portion ofthe edifice where the program is to be performed.

In testimony whereof, I have hereunto subscribed my name this 17th dayof March,

ALEXANDER NYMAN.

